Waters ACQUITY UPLC M-Class System Manual page 70

4.3.2.9 Fronting peaks
Suspected cause
Injection volume or sample concentration is too
high, disrupting column equilibrium.
Sample diluent is too high in organic for the
initial mobile phase.
Needle weak wash solvent is too high in the
organic sample.
Column or pre-column is contaminated.
Column degraded forms a void.
Trap column is degraded.
4.3.2.10 Missing peaks
Suspected cause
Wrong sample injected
Degraded or contaminated sample or standard
Loss of resolution
Possible solution
Reduce the injection volume or dilute the
sample.
Reduce the injection volume or reduce the
percentage of organic.
Ensure that the weak needle wash solution is
similar to the initial mobile phase.
Note:
should be three times strong wash volume.
Clean the column or pre-column or replace.
See also:
use guide on the documentation CD.
Verify column performance. If efficiency is low,
replace it.
Possible solution
Check or replace the sample.
November 26, 2019, 715003588 Revision C
Page 70
The volume of weak needle wash
The appropriate column care and
• Remove the trap column and perform a
direct injection.
• If results are normal, replace the column
and perform a set pressure diagnostic.
• Inject a known good standard.
• If the fewer peaks problem persists, use
fresh mobile phase and flush the system.
• If fewer peaks persist, clean or replace the
column.
• Check the fluidic connections for dead
volumes.
• Change your column.
• Verify if It is time to service the mass
spectrometer.
• Confirm the vial location.